1. Field of the Invention
The present invention relates to a polycrystalline MgO deposition material which is a raw material of MgO film used as the passivation layer of an AC type plasma display panel, and more particularly, to a polycrystalline MgO deposition material which is a raw material of MgO film having a good response characteristic in a wide temperature range and an AC type plasma display panel using the MgO film.
2. Discussion of the Related Art
In recent, research and development for a variety of flat panel displays including a liquid crystal display (LCD) have been actively performed so that their utilization has been remarkably advanced and production is being increased sharply. The drift for development and utilization of a color plasma display panel (hereinafter referred to as “PDP”) is also being actively performed. PDP has an advantage of a large-sized screen. In real, a PDP with a diagonal length of 40 inches in the shortest distance of a large-sized hang-on-the-wall TV for a hivision is being fabricated. PDPs are classified into an AC type PDP in which the metal electrode is covered with dielectric glass material and a DC type PDP in which the metal electrode is exposed to a discharge space according to the electrode structure.
In an initial developing stage of the AC type PDP, since the dielectric glass layer is directly exposed to the discharge space, the surface of the dielectric glass layer is deformed by an ion impact of sputtering and thereby discharge start voltage is elevated. To this end, there were tries to use various oxides having a high sublimation heat as the passivation layer of the dielectric glass layer. The passivation layer plays an important role because it is in direct contact with the discharge gas. In other words, the passivation layer should satisfy the following conditions of (1) low discharge voltage, (2) sputtering-resistant capability in discharge, (3) rapid discharge response, and (4) insulation. MgO is a material to satisfy the above four conditions and is used as the passivation layer. The passivation layer of MgO protects the surface of the dielectric glass layer from sputtering on discharge and plays an important role in lengthening the life of the PDP.
However, MgO has a drawback in that when used as the passivation layer, display scattering called “black noise” is frequently generated. Black noise is a kind of scattering phenomenon in which a to-be-turned-on cell (selected cell) is not turned on, and it is known that the black noise is easily generated at a boundary between the to-be-turned-on region and the not-to-be-turned-on region. Since all the selected cells on one line or one column are not turned on but its generation region exists sporadically, the black noise is determined as an address miss in which address discharge is not generated or if generated, its intensity is insufficient.
As a way to solve the aforementioned all the problems, disclosed is a PDP (see cited patent reference 1), which uses an MgO film formed by an vacuum evaporation method and containing Si in a ratio of 500–10,000 ppm by weight. In the cited reference 1, there is disclosed a fact that the address miss that is a reason of the black noise is suppressed because the MgO film contains Si in the aforementioned ratio.
In the cited patent reference 2, disclosed is a PDP, which uses an MgO film containing Si in a ratio of 1,000–40,000 ppm by weight by a thermal decomposition of fatty acid salt as the sputtering-resistant film. According to the cited reference 2, the electrical characteristic of the PDP is improved by a micro component contained in the MgO film formed by the thermal decomposition of the fatty acid salt. Also, discharge amount of secondary electrons is increased, lowering in effective voltage due to residual charge is supplemented and the residual of charges is reduced and rapidly lost, so that the address miss acting as the black noise can be suppressed.
In the meanwhile, it is known that the response of the PDP is influenced by various conditions of discharge cell shape, applied voltage on operation of PDP, frequency and the like (for instance, see cited non-patent reference 1). The non-patent reference 1 discloses a method for evaluating response of PDP.
In addition, it is known that the response is improved by irradiating vacuum ultraviolet rays in discharge cells (for instance, see cited non-patent reference 2). The non-patent reference 2 also disclose a method for evaluating response of PDP.